<?PHP

namespace Monperrus\BibtexBrowser;

class StateBasedBibtexParser
{

    var $delegate;

    public function __construct($delegate) {
        $this->delegate = $delegate;
    }

    public function parse($handle) {
        if (gettype($handle) == 'string') { throw new Exception('oops'); }
        $delegate = $this->delegate;
        // STATE DEFINITIONS
        @define('NOTHING',1);
        @define('GETTYPE',2);
        @define('GETKEY',3);
        @define('GETVALUE',4);
        @define('GETVALUEDELIMITEDBYQUOTES',5);
        @define('GETVALUEDELIMITEDBYQUOTES_ESCAPED',6);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS',7);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_ESCAPED',8);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL',9);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL_ESCAPED',10);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL',11);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL_ESCAPED',12);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL',13);
        @define('GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL_ESCAPED',14);


        $state=NOTHING;
        $entrytype='';
        $entrykey='';
        $entryvalue='';
        $fieldvaluepart='';
        $finalkey='';
        $entrysource='';

        // metastate
        $isinentry = false;

        $delegate->beginFile();

        // if you encounter this error "Allowed memory size of xxxxx bytes exhausted"
        // then decrease the size of the temp buffer below
        $bufsize=BUFFERSIZE;
        while (!feof($handle)) {
            $sread=fread($handle,$bufsize);
            //foreach(str_split($sread) as $s) {
            for ( $i=0; $i < strlen( $sread ); $i++) { $s=$sread[$i];

                if ($isinentry) $entrysource.=$s;

                if ($state==NOTHING) {
                    // this is the beginning of an entry
                    if ($s=='@') {
                        $delegate->beginEntry();
                        $state = GETTYPE;
                        $isinentry = true;
                        $entrysource='@';
                    }
                }

                else if ($state==GETTYPE) {
                    // this is the beginning of a key
                    if ($s=='{') {
                        $state = GETKEY;
                        $delegate->setEntryType($entrytype);
                        $entrytype='';
                    }
                    else   $entrytype=$entrytype.$s;
                }

                else if ($state==GETKEY) {
                    // now we get the value
                    if ($s=='=') {
                        $state = GETVALUE;
                        $fieldvaluepart='';
                        $finalkey=$entrykey;
                        $entrykey='';
                    }
                    // oups we only have the key :-) anyway
                    else if ($s=='}') {
                        $state = NOTHING;$isinentry = false;$delegate->endEntry($entrysource);
                        $entrykey='';
                    }
                    // OK now we look for values
                    else if ($s==',') {
                        $state=GETKEY;
                        $delegate->setEntryKey($entrykey);
                        $entrykey='';}
                    else { $entrykey=$entrykey.$s; }
                }
                // we just got a =, we can now receive the value, but we don't now whether the value
                // is delimited by curly brackets, double quotes or nothing
                else if ($state==GETVALUE) {

                    // the value is delimited by double quotes
                    if ($s=='"') {
                        $state = GETVALUEDELIMITEDBYQUOTES;
                    }
                    // the value is delimited by curly brackets
                    else if ($s=='{') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS;
                    }
                    // the end of the key and no value found: it is the bibtex key e.g. \cite{Descartes1637}
                    else if ($s==',') {
                        $state = GETKEY;
                        $delegate->setEntryField($finalkey,$entryvalue);
                        $entryvalue=''; // resetting the value buffer
                    }
                    // this is the end of the value AND of the entry
                    else if ($s=='}') {
                        $state = NOTHING;
                        $delegate->setEntryField($finalkey,$entryvalue);
                        $isinentry = false;$delegate->endEntry($entrysource);
                        $entryvalue=''; // resetting the value buffer
                    }
                    else if ($s==' ' || $s=="\t"  || $s=="\n" || $s=="\r" ) {
                        // blank characters are not taken into account when values are not in quotes or curly brackets
                    }
                    else {
                        $entryvalue=$entryvalue.$s;
                    }
                }


                /* GETVALUEDELIMITEDBYCURLYBRACKETS* handle entries delimited by curly brackets and the possible nested curly brackets */
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS) {

                    if ($s=='\\') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_ESCAPED;
                        $entryvalue=$entryvalue.$s;}
                    else if ($s=='{') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL;
                        $entryvalue=$entryvalue.$s;
                        $delegate->entryValuePart($finalkey,$fieldvaluepart,'CURLYTOP');
                        $fieldvaluepart='';
                    }
                    else if ($s=='}') { // end entry
                        $state = GETVALUE;
                        $delegate->entryValuePart($finalkey,$fieldvaluepart,'CURLYTOP');
                    }
                    else {
                        $entryvalue=$entryvalue.$s;
                        $fieldvaluepart=$fieldvaluepart.$s;
                    }
                }
                // handle anti-slashed brackets
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_ESCAPED) {
                    $state = GETVALUEDELIMITEDBYCURLYBRACKETS;
                    $entryvalue=$entryvalue.$s;
                }
                // in first level of curly bracket
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL) {
                    if ($s=='\\') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL_ESCAPED;
                        $entryvalue=$entryvalue.$s;}
                    else if ($s=='{') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL;$entryvalue=$entryvalue.$s;}
                    else if ($s=='}') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS;
                        $delegate->entryValuePart($finalkey,$fieldvaluepart,'CURLYONE');
                        $fieldvaluepart='';
                        $entryvalue=$entryvalue.$s;
                    }
                    else {
                        $entryvalue=$entryvalue.$s;
                        $fieldvaluepart=$fieldvaluepart.$s;
                    }
                }
                // handle anti-slashed brackets
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL_ESCAPED) {
                    $state = GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL;
                    $entryvalue=$entryvalue.$s;
                }

                // in second level of curly bracket
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL) {
                    if ($s=='\\') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL_ESCAPED;
                        $entryvalue=$entryvalue.$s;}
                    else if ($s=='{') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL;$entryvalue=$entryvalue.$s;}
                    else if ($s=='}') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_1NESTEDLEVEL;$entryvalue=$entryvalue.$s;}
                    else { $entryvalue=$entryvalue.$s;}
                }
                // handle anti-slashed brackets
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL_ESCAPED) {
                    $state = GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL;
                    $entryvalue=$entryvalue.$s;
                }

                // in third level of curly bracket
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL) {
                    if ($s=='\\') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL_ESCAPED;
                        $entryvalue=$entryvalue.$s;}
                    else if ($s=='}') {
                        $state = GETVALUEDELIMITEDBYCURLYBRACKETS_2NESTEDLEVEL;$entryvalue=$entryvalue.$s;}
                    else { $entryvalue=$entryvalue.$s;}
                }
                // handle anti-slashed brackets
                else if ($state==GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL_ESCAPED) {
                    $state = GETVALUEDELIMITEDBYCURLYBRACKETS_3NESTEDLEVEL;
                    $entryvalue=$entryvalue.$s;
                }

                /* handles entries delimited by double quotes */
                else if ($state==GETVALUEDELIMITEDBYQUOTES) {

                    if ($s=='\\') {
                        $state = GETVALUEDELIMITEDBYQUOTES_ESCAPED;
                        $entryvalue=$entryvalue.$s;}
                    else if ($s=='"') {
                        $state = GETVALUE;
                    }
                    else {  $entryvalue=$entryvalue.$s;}
                }
                // handle anti-double quotes
                else if ($state==GETVALUEDELIMITEDBYQUOTES_ESCAPED) {
                    $state = GETVALUEDELIMITEDBYQUOTES;
                    $entryvalue=$entryvalue.$s;
                }

            } // end for
        } // end while
        $delegate->endFile();
        //$d = $this->delegate;print_r($d);
    } // end function
} // end class